You write a letter informing ALL employees that they must make sure they have clean clothes and smell "proper."
This way, you do not alienate anybody in particular, and if any employee asks "what is this for?" you can tell them 'John Smith has smelled like burnt ass way too many times for my liking, and since I can't get him in trouble for attempting to hook up with 14 year olds, I at least need to make sure my workplace doesn't allow him to stink up the place like onions being cooked with garlic!'